Broadband data communications using some form of Digital Subscriber Loop or Line (DSL) for the general population over guided media, e.g., telephone Wireline, have encountered a practical and economical limit. There are several different kinds of communication techniques currently in use that are mutually incompatible yet try to cover various combination of data rate and distance, e.g., high bit-rate DSL (HDSL), HDSL II, asymmetric DSL (ADSL), G.lite (known as universal ADSL), symmetric DSL (SDSL), very high bit-rate DSL (VDSL), G.SHDSL (an international standard for symmetric DSL developed by the International Telecommunications Union (ITU)), integrated services digital network (ISDN), T-1, etc. These various communication techniques employed by the different broadband services involve tradeoffs between data rates and serviceable distance (i.e., service area). Also, the shortcomings of DSL are well known to one skilled in the art and are the driving factors behind the frequent evolution in DSL formats. Distances beyond three miles from the telephone company's (or Telco's) central office (CO) are rarely served by the current DSL system.
It is appreciated that data rates above 1.5 Mbps for low cost DSL services threaten the telephone companies' lucrative T-1 service, a dedicated phone connection supporting data rates of 1.544 Mbits per second. A T-1 line consists of 24 individual channels, each of which supports date rates of 64 Kbits per second. Various DSL services can provide data rates above 4–6 Mbps, but their service range is restricted to less than half a mile. The latest and most expensive DSL service, VDSL, can provide data rates over 20 Mbps and is restricted to less than 1 mile.
With existing asymmetric DSL systems, such as ADSL, VDSL and G.lite, higher data rates can be achieved in one direction at the expense of the return data path, such as providing more bandwidth going downstream from the Internet to the user and less bandwidth going upstream from the user to the Internet. However, these upstream and downstream bandwidth allocations are predefined in the design and cannot be customized to meet an individual customer's needs. The number of data rates currently available to customers is fixed by the design limitations of the existing or fielded systems. That is, the particular date rates of a given DSL system can be provided only to those customers who are located within the system specified distance (i.e., service range) from the Telco's central office. The DSL system cannot provide services to those customers who are located outside the service range.
Additionally cable, terrestrial broadcast radio frequency (RF) and satellite services suffer from a fixed bandwidth broadcast-based topography that causes the data rates to diminish almost proportionately with increased number of customers and demand. That is, these current broadbased systems are not easily scalable, thereby posing problems for broadbased applications requiring large bandwidths. In cable systems, the cable or service provider generally dedicates a video channel's bandwidth of 6 MHZ for broadband service to generate approximately 40 Mbps of data rate over a coax shielded cable guided media path. This enables the cable provider to provide 200 kbps data rate service to 200 customers. However, peak rates can be much higher which can pose a potential problem if it is fully loaded with 200 customers.
Satellite systems have a similar fixed bandwidth problem today. Each of the 24 transponders on a Galaxy class DES satellite from Hughes Communications, Inc. (see http://www.adec.edu/satdb/gal4rku.html) is a 36 MHz RF channel to cover a terrestrial footprint equal to the East Coat and inland for about 500 miles. Assuming a data rate of 100 Mbps for this RF channel, then the satellite provider can provide 400 kbps data rate service to 250 customers, which translates to 6000 customers if the entire satellite's 24 transponder channels are used. However, this system does not scale up easily without severe dilution, thereby posing potential problems for broadbased application requiring large bandwidths.
In the cable case, uplink detracts from downlink bandwidth and the number of net new paying customers. In the satellite case, uplink is by slow dial-up phone line (i.e., low data rate)
The nature of the frequency based signal modulation technique of DSL makes it very sensitive to cross-talk from ISDN and T-1 services as well as other DSL channels in the same cable grouping/binder. Accordingly, this further limits the number of customers that can be served in a common wire bundle. The servicing company, whether a Telco (i.e., an incumbent local exchange carrier or ILEC) or a competitive local exchange carrier (CLEC), has to qualify the telephone line for broadband service typically by sending a technician out in a truck to evaluate the line which can be time consuming and expensive. The technician often changes the selection of wire pairs in the wire bundles to get the best connections. This process can be expensive and frequently leads to follow-up service calls due to technician error. Also, bridged taps along the Wireline reduce availability and performance of the DSL service. Additionally, all of the frequency based services have many discrete frequency tonals that can radiate into AM and Ham Radio frequency bands. All of these factors have resulted in a virtual cap on the size of the servable customer base for the current DSL system. Hence, the percentage of U.S. households with DSL service or the DSL household penetration has been limited to about three percent of the total U.S. households. In other words, the current DSL services represent approximately only three percent of the total Wireline market.
Therefore, it is desirable to expand the current broadband market presence by providing a broadband system and method that goes beyond the performance limits of current broadband systems, including various types of DSL systems, and minimize their associated technical and business weaknesses.